GB140789A - Automatic control mechanism for electric furnaces - Google Patents

Abstract

140,789. Scovill Manufacturing Co., (Assignees of Bennett, M. H.). June 26, 1918, [Convention date]. Electrode furnaces.-An automatic controller, maintaining constant both the power supplied to a furnace and the proportion of this power delivered by each of a number of electrodes, is responsive to unbalanced changes in the current, the pressure, or the power factor. As shown, each electrode 2, 3, or 4 of a 3-phase furnace is adjusted by a reversible motor 30, 31, or 32, to the armature of which current can be directed through either of two oppositely-wound field coils by a switch lever 54 and fixed contacts 38, 40 from direct-current mains 33, 41. Each arm of the switch lever carries a coil moving between two fixed coils. The three coils 57 - - 59 of one set are all in series in a circuit from the supply conductor 7 of electrode 2 to a hearth contact 67. Of the other set of coils, which oppose the first set, the two outer 74, 75 are in series with a transformer 77 in the supply conductor 7, while the movable coil 73 is connected to the supply conductor 7 and either to a neutral point or, as shown. to the supply conductor 6 to another electrode 3, so as to form a delta arrangement with the corresponding coils of the other regulators. A rheostat 81 is in circuit with the pressure coil 73.